Purification of benzene or its



April 27, 1954 H. SCHWENKE PURIFICATION OF BENZENE OR ITS HOMOLOGUESFiled Sept. 28, 1949 Patented Apr. 27, 1954 PURIFICATION OF BENZENE ORITS HOMOLOGUES 5 Hermann .Schwenke, Kanien westphalia, Germany,assignor, by mesne, assignments, to. K91

P Company, Inc Pittsburgh Pa acorpo-v ration ofDelaware ApplicationSeptember 28, 1949-, Serial No 118,315

Claims priority,'appli cation Germany October 1,1948 7 8 Claims. (01.260-.-674) The present invention relates broadly to the purification ofbenzene or its homologues and more particularly to the purificationofsaid hydrocarbons in the vapour phase.

"The removal of resin forming agents (unsaturated hydrocarbons) andother impurities from raw benzene for the purpose-of recovering motorbenzene has previously been effected by treatment withfstrong sulphuricacid followed by washing with soda lye. This method of operaticn 'isabove alLattended with considerable losses since in a secondary;reaction benzenesulphonic acid is formedwhich may frequently amount to645% of the raw benzene being treated. Moreover, the Workingup of thewaste acid-from the henzone purification is troublesome since it has notyetbeen, found possible to find an effective use for the materialseparated by the sulphuric acid.

It hasalready been proposed to free benzene from sulphur" compounds bypassingit.- the vapour phase over solid contact substaneesfi'it has, forexample been proposed to oonduct raw benzene, in the-form of vapour attemperatures of coo-450%., over minette. This working-itemifperatureshowever, in practice makes it necessary to employ: an apparatusprovided with gasgfiring or the like which involve the operation in considerable-danger.

An object ofithe present invention is to provide for such-improvementsin thepurification of benzene orits homologuesvrhioh will render thepurification of::said-hydrocarbons in the vapour phase more .efiicientlyat temperatures usual to distillation practice so that apparatus and.heat inglmeans :usual/in the operation oi 'by-product ordistillationplants may-be: employed;

According to an essential feature of the in' ventionthe purification: ofbenzene :or its homologues isefifectedby vapourising- -the ratv maeterialito he purified and, bringing thevapours so produced, in 'a heatedcondition, into contact with a'solid mixture of alkaline ferrichydroxide and fulleifls earth or. the like (aluminium magnesiumsilicate) at increased temperature. 7 I

Considerableadvantages are obtainedhy the employment of -the invention.Firstly, as regards operating temperature, it is suflicient: in generaltov treat. vapours ant-temperatures below about 250 C.., that is, in arange within which the heating of the apparatus can be carried outwiththe'high pressure steam normallyavailable in in- V dustry. -P referably,the treatment is carried out at atemperature' of between lOO and 150 C.

This temp'erature liesonly slightly'above the distillation temperature.The composition and the Z properties of the raw :-materials and heimpurities determine what treatment temperature, within the statedlimits inthe: process accord-: ingto the invention gives the;bost-effeotbothas regards 'theuremoval of impurities and also-thodurabilityof the solid treatment :me'dia; Genorally, the lower thetemperature maintained; the greater is their life; 1"- r It isadvantageouspreviomly to. rectify the hydrocarbon oilto he treatedandtorwithdraw the first running separately. This first running consists inthe case of the-preparation, .oihonzene for the purposeofobtaining;motor-benzene-or purified benzene, ofi materials boilingbelow 79 C. and contains chiefly carbonvdisulphideland cyclopentadiene:The. benzenegor the :like vfreed from the first: running is'then.vaporised and the vapour treatedaocording: to the rinvention. The,solid; purification masses with which; the v pours of the hydrocarb noil-- benzene an /or homologueslto tie-purifiedarerbroughtinto com tactcontain asa substantial constituent alkaline ferric hydroxide andfullers 1 earth. (aluminium magnesiumsilicate). The ierric .hydroxidelispreferably employed. in the form. of the. s -call d purifying mass. forindustrial .gas (for. example, coal gas) and particularlythelsoscallecl, fine purification mass which serves-fertile removal oforgai'iio sulphur compoundsirom such gases,

and from which valuable hydrocarbons are formed psi-synthesis. Such amass consists for example of a mixture oil-700 kilograms of: hog ironorthelike audited-kilograms of soda. ljhese constituents areymixedhotpand the re u n product prefetably-w granulated into particles whichfertile-purpose. oi thetreatment of hy carbon vapours according otheinvention may be of about 0515' millimetres. I

The granular alkaline-ionic hydroxide mass is associated withiullerisaearth .ina catalyst bed.

Advantageously: the two. are. simply mixed to gather. :It islhowevei,also possible to arrange the material and the .fullers earth in thinlayers iii-alternate seouenceinlthe treatment apparatus, asiorexample onperforated partitions. Th two. materials may also be arranged loosely inI the treatment apparatus and withlsuch agrain size that-abed isformedwhich isl'sept in movement by the vapours: passing thcretliroughi Forthis purpose the grain size otthe ferric hydroxide mass-and the.iulleris' earthmust been chosen that axsubstantialseparation-cities.6011* stituents' or thelrmixture leann tccour when themixtureis iiiovedor; stirred-an by the'vapours Instead of toilets earth;other'fsuriaee active materials can be employed, particularly materialscontaining clay and silicic acid, such as for examplealuminium-magnesium silicate, which may if desired [be previouslysubjected to a special activation, as for example with hydrochloricacid.

After the treatment apparatus is supplied with the mixture of solidmaterials it is heated to the required reaction temperature in order toprevent undesired condensation of the hydrocarbons, and the hydrocarbonvapours may then be continuously applied thereto. .The supply of thevapours to and from the apparatus is carried out in such a way that theyflow through the mixture in the apparatus and come into intimate contactwith the solid or granular materials.

After the vapours leave the treatment apparatus they are condensed. Inthe treatment of benzene in this manner a condensate is obtained whichmay be employed without further treatment as motor benzene.

The loss in hydrocarbon oil through the purification is, in thetreatment of benzene according to the process of the invention, about1.35-1.50% (by weight). The content of resinforming constituents in thebenzene decreases from about 15 mg. in the raw benzene to about 2 mg. orless in the motor benzene. The product of purification is free fromsulphur. It shows no further reaction on treatment with sulphuric acid(BO-66 Baum) in the cold.

The purity of the product is sufiicient in order for example, to makebenzene suitable for combustion engines by a single treatment of thevapours with the-fixed purifying mass. If a still higher purity isdesired it is possible according to the invention to treat the vapours,after treatment with the solid purifying mass, and without substantialvariation in temperature, with hot sulphuric acid (about 64 Baum), andthen with hot soda lye (about 30%) or the like. Through this subsequenttreatment the purification loss is increased somewhat, e. g. in the caseof benzene, to about 2.5%. The end product is however, of. the greatestpurity, previously only btainable with considerably higher losses By wayof example, the process was carried out as follows:

A thousand kg. of a granular mixture of 700 kg. of bog iron ore and 300kgs. of soda,'which may be in the form of the so-called Lux-mass, weremixed in theunscreened condition with a thousand kg. of fullers earth,likewise unscreened. The treatment temperature at which the vapoursproduced by distillation of the raw benzene after separation of thefirst running, v

are brought into contact with the mixturalay between 190 and 150 C. Withcontinuous operation. 600 to 800 T. of raw benzene and more can bepurified with the mixture. The resinformer test of the raw benzeneamounted to mg. By the treatment of the benzene vapours the resin formertest dropped to 2 mg. The product fulfilled the requirements for motorbenzene.

It is advantageous to withdraw the vapours of the benzene, toluene andxylene, including the higher homologues, separately from the treatmentaccording to the invention, the treatment temperatures naturallybeing sochosen for this purpose, that the treated hydrocarbons remain in thevaporised condition.

In certain conditions the treatment accordin to the invention can beemployed in combination with a fractional distillation, the vapouroutlets of each fraction being provided with an apparatus for treatmentof the vapours with the de scribed solid mixture, from which the vapoursthen pass into the condenser of the usual kind.

The drawing illustrates diagrammatically an apparatus suitable forcarrying out the purification of benzene or its homologues according tothe invention.

The hydrocarbon oil to be purified, for example, raw benzene, enters theapparatus at i. It then goes through the heat exchanger 2 and passes inthe preheated condition through the conduit 3 into the distillationvessel 4. In this the liquid is indirectly heated by steam which isintroduced through the conduit 5 and the resulting condensate flows awaythrough the pipe 6.

The hydrocarbon vapours produced in the vessel 4 are drawn off throughthe pipe 1 and pass through the pipe 8 to a superheater 9 in which thevapours are superheated in the desired manner. From the superheater 9the pipe ll! leads to a closed treatment apparatus H which is acketedexternally-as indicated at i2-with an nsulating material and is providedwith a heatmg coil l3.

A solid granular mixture of alkaline ferric hydroxide and fullers earthor the like is arranged in the apparatus I l on a perforated partitionor the like, not illustrated. The vapours come into contact with thefilling of the apparatus H and then pass out through the pipe M which iscontrolled by a valve l5. The vapours then pass into an apparatus 25 inwhich they are brought into contact with hot sulphuric acid at increasedtemperature, so that no condensation can occur. The vapours then passthrough the pipe Hi into an apparatus I! in which they are treated withhot soda lye or the like. The purifled vapours finally pass through thepipe H! to the heat exchanger 2, constructed as a cooler, and thecondensate may be withdrawn at Hi.

In order to preheat the apparatus II and its solid granular contents tothe correct operating temperature a spec al circulating fan 20 may beprovided. After opening the valve 22 and closing the valve 23, this fanmoves air or steam through the pipes 2|, 8. to the superheater 9. Theheated vapours then flow through the apparatus H and there give up theirheat, whereafter they are returned through the pipe I after closure ofthe valve I5 and openin of the valve 24, through the pipe 25 to the fan2!), so that air or other gas or vapours can be circulated through thesuperheater and the apparatus H. As soon as the latter has reached thedesired temperature the blower 20 is stop ed. the valves 22 and 224closed and the valves 23 and !5. opened, and the treatgegiiigof thevapours from the vessel 4 can then The invention as hereinabove setforth is embodieddn particular form and manner but may be variouslyembodied within the scope of the claims hereinafter made.

I claim:

1. In a process for removin r i r 1' constituents from material selectedis $6 consisting of raw benzene and a benzene toluene or xylene fractionthereof. for the recovery oi motor iuel from said material, the stepsof" vaporizing said materials after separation or fore runnings whichboil below 79 (73., and passing the vapors through a solid material compising alkaline ferr c hydroxide and surface active sili- ClOllS catalysta temperature below (i but allay; C. reinove resin-forming constim'saimaceria purified material. 1 andrecovering the so 2. In a process forremoving resin-forming constituents from material selected from theclass consisting of raw benzene and a benzene, toluene, or xylenefraction thereof, for the recovery of motor fuel from said material, thesteps of: rectifying said material to take off as forerunningsimpurities, including carbon disulphide and cyclopentadiene, which boilbelow 79 C.; vaporizing the rectified material and passing the vaporsthrough solid material comprising alkaline ferric hydroxide and surfaceactive silicious catalyst at a temperature below 150 C. but above 100 C.to remove resin-forming constituents from said material, and recoveringthe so purified material.

3. A process as claimed in claim 2, and in which the alkaline ferrichydroxide is in the form of the so-called fine purification Lux-mass ofgranular particles of bog iron and soda ash.

4. A process as claimed in claim 2, and in which the alkaline ferrichydroxide is a mixture of ferric hydroxide and soda ash, and in whichthe surface active catalyst is in admixture with the alkaline ferrichydroxide.

5. A process as claimed in claim 2, and in which the surface activecatalyst is an acid activated aluminum-magnesium silicate.

6. A process as claimed in claim 2 and in which the recovered materialis thereafter treated first References Cited in the file of this patentUNITED STATES PATENTS Number Name Date 1,759,812 Gray May 20, 19301,882,000 Cross Oct. 11, 1932 1,944,877 Darlington Jan. 30, 19342,134,241 Susselbeck Oct. 25, 1938 2,151,721 Schulze Mar. 28, 19392,433,426 Capell et al Dec. 30, 1947 2,559,323 Spillane July 3, 1951OTHER REFERENCES Gas Age-Record, vol. 58, pages 73-6, July 17, 1926.

1. IN A PROCESS FOR REMOVING RESIN-FORMING CONSTITUENTS FROM MATERIALSELECTED FROM THE CLASS CONSISTING OF RAW BENZENE AND A BENZENE,TOLUENE, OR XYLENE FRACTION THEREOF, FOR THE RECOVERY OF MOTOR FUEL FROMSAID MATERIAL, THE STEPS OF: VAPORIZING SAID MATERIALS AFTER SEPARATIONOF FORERUNNINGS WHICH BOIL BELOW 79* C., AND PASSING THE VAPORS THROUGHA SOLID MATERIAL COMPRISING ALKALINE FERRIC HYDROXIDE AND SURFACE ACTIVESILICIOUS CATALYST AT A TEMPERATURE BELOW 150* C. BUT ABOVE 100* C. TOREMOVE RESIN-FORMING CONSTITUENTS FROM SAID MATERIAL, AND RECOVERING THESO PURIFIED MATERIAL.